bracket sequence checker

#include "bits/stdc++.h"

using namespace std;

int main () {
	 ios::sync_with_stdio(false);
	 cin.tie(nullptr);
	 cout.tie(nullptr);
	 string s = "()()(())((()))"; // open = 1
	 int open = 0;
	 int n = (int) s.size();
	 //~ bool f = true;
	 for (int i = 0; i < n; ++i) {
		 if (s[i] == '(') {
			 ++open;
		 } else {
			 --open;
		 }
		 if (open < 0) {
			 //close bracket beshi ache
			 cout << "INVALID\n";
			 return 0;
		 }
	 }
	 //ekhane asar mane hocche open < 0 execute hoy ni
	 if (open > 0) {
		 //open bracket beshi ache
		 cout << "INVALID\n";
	 } else {
		 cout << "VALID\n";
	 }
}